Orbit and Cranial Nerves of Eye

Question 1

What bone(s) make up the superior wall of the orbit?

Answer 1

frontal

lesser wing of sphenoid

Question 2

What bone(s) make up the medial wall of the orbit?

Answer 2

mostly ethmoid

Question 3

What bone(s) make up the lateral wall of the orbit?

Answer 3

zygomatic

greater wing of sphenoid

Question 4

What bone(s) make up the inferior wall of the orbit?

Answer 4

mostly maxilla

zygomatic

Question 5

What are the contents of the orbit?

Answer 5

eye, optic nerve, blood vessels, muscles, nerves, fat

Question 6

Levator palpebrae attachments?

Answer 6

O: lesser wing of sphenoid
I: aponeurosis of eyelid

Question 7

Orbicularis oculi attachments?

Answer 7

O: nasal portion of frontal bone
I: fascia of eyelids and skin around orbit

Question 8

4 Rectus Muscle attachments?

Answer 8

O: all 4 arise from tendinous ring at back of orbit
I: sclera of eye

Question 9

Superior oblique attachments?

Answer 9

O: medial roof of orbit
I: posterolateral eye

Question 10

Inferior oblique attachments?

Answer 10

O: orbital surface of maxilla
I: posterolateral eye

Question 11

Levator palpebrae superioris innervation and action?

Answer 11

N: occulomotor (CN III)
A: opens eyelid

Question 12

Orbicularis occuli innervation and action?

Answer 12

N: facial (CN VII)
A: closes eyelid
BELLS PALSY

Question 13

The tendon of the ________ passes through a pulley system.

Answer 13

superior oblique

Question 14

CN III is responsible for all extraoccular movements with the exception of…

Answer 14

ABduction by Lateral Rectus (CN VI abducens)

depression and intorsion by superior oblique (CN IV trochlear)

Question 15

Depression and extorsion of increases with ______ .

Answer 15

ADduction

Question 16

Intorsion and elevation increases with _______.

Answer 16

ABduction

Question 17

Where is occulomotor nucleus located?

Answer 17

rostral midbrain

Question 18

CN ____ provides preganglionic parasympathetic fibers to ciliary ganglion

Answer 18

CN III

innervates sphincter of iris for pupillary light reflex

Question 19

If an individual cannot ADduct or elevate, deficit is called

Answer 19

lateral strabismus

CN III

Question 20

If an individual cannot ABduct, deficit is called

Answer 20

medial strabismus

CN VI

Question 21

Lesion to CN IV may appear normal at rest, but deficit involves which movement?

Answer 21

cannot depress when Adducted

Question 22

What is exotropia?

Answer 22

lateral strabismus: unopposed lateral rectus

eye rests in ER position

Question 23

What are tests for CN III lesion?

Answer 23

eye movement
pupillary light reflex
vergence (pupils constrict as objects get closer)

Question 24

What are the two components of pupillary light reflex?

Answer 24

CN II = sensory

CN III = motor

Question 25

Diploplia, eyelid ptosis at rest, myadriasis (dilation of pupil) are signs of?

Answer 25

lesion of CN III

Question 26

Trochlear nucleus is located where?

Answer 26

caudal midbrain

Question 27

What nerve supplies the superior oblique muscle?

Answer 27

CN IV trochlear

Question 28

CN IV lesion presents with

Answer 28

inability to move eye inferior when ADducted, diploplia, hypertropia (affected eye vertically deviated upward/extortion)

Question 29

Abducens nucleus is located where?

Answer 29

caudal pons

Question 30

What nerve supplies lateral rectus muscle?

Answer 30

CN VI abducens

Question 31

What is esotropia?

Answer 31

medial strabismus - inability to ABduct the eye | sign of CN VI lesion

Question 32

When the eye is ADducted, the superior oblique moves the eye _______.

Answer 32

inferiorly

Question 33

When the eye is ADducted, the inferior oblique moves the eye _______.

Answer 33

superiorly

Question 34

Name this lesion: With gaze straight ahead, right eye abducted because of weakness of medial rectus, right eyelid droops, and pupil is dilated.

Answer 34

R occulomotor lesion (CN III)

Question 35

Name this lesion: With gaze L, right eye adducts but is elevated owing to weakness of superior oblique muscle.

Answer 35

R trochlear lesion (CN IX)

Question 36

Name this lesion: With gaze R, right eye does not abduct because lateral rectus muscle is weak.

Answer 36

R abducens palsy (CN XI)